Various types of heat engines have supplied shaft work that energized the Industrial Revolution. Currently, internal combustion engines, specifically piston engines, provide the shaft work that enables a large portion of modern mobility and productivity. It is estimated that there is one piston engine powered vehicle for every ten persons on Earth and that more than 800 million piston engines are operated throughout the world.
Although conventional piston engines provide valuable mechanical energy, well known problems are presented by the efficiency limitations imposed by current engine designs. For example, conventional engines more heat than the amount of energy provided as output work. The energy wasted on unused heat reduces the overall efficiency of conventional engines and increases their operating costs.
In addition to efficiency losses from wasted heat, friction losses significantly reduce the overall efficiency of engines and/or the vehicles or machines that they power. For example, most automobiles include transmissions, differentials, and other components that are coupled to a vehicle's engine. These additional mechanical components are necessary because the relatively high rate of rotation of the crankshaft in most internal combustion engines requires a transmission to reduce the rotational speed to match a desired rotational tire speed. Additionally, differentials are often required to adjust the rotational speed of individual tires during cornering or in other situations that require wheel rotation at different rates. Each additional mechanical component between the engine and the tires introduces further opportunities for efficiency losses. Friction and heat losses in the transmission, the differential, or other components can thereby further reduce the efficiency of the vehicle. Accordingly, it is desirable to reduce these efficiency losses and provide an engine that can operate with greater overall efficiency.